Setting mosaic floor tile

Hi - I'm getting ready to do a bath floor tile installation using 12x12 mosaic sheets (Black/White pinwheel pattern). Any tips for applying the thinset? I've done mosaics before on backsplashes and always wind up with the thinset oozing up thr ough the tile. On a small area it's not that bad to deal with but on a large floor it would be a pain. Thanks for any advice.

I went over to JohnBridge and got some good information...Thanks.